asked on

last day of the month

How do I test for the last day of the month?

here is what I am trying to do

function addEndDte(){
                              //alert(isDate(dte.value))
                              dte=BudgetCopy.BegDte.value;
                              if(isDate(dte)){
                                    d="";
                                    d=new Date(dte)
                                    d.setMonth(d.getMonth()+4)
                                    d.setDate(31)
                                    document.BudgetCopy.EndDte.value=twod(d.getMonth()*1+1) + "/" + twod(d.getDate()) + "/" + d.getFullYear();

                              }else{
                                    setTimeout("addEndDte()", 200);
                              }
                         }

if the month is Feb. and I try to add this d.setDate(31) its going to make the month March and thats not what I want it to do.

cLFlaVA

Why not do this instead?

d.setMonth(d.getMonth()+5)
d.setDate(-1)

knightEknight

so, what you want to do is set the date to the last day of a given month?

instead of this:
d.setMonth(d.getMonth()+4)
d.setDate(31)

do this:
d.setMonth(d.getMonth()+5)
d.setDate(1)
d.setDate( d.getDate()-1 )

knightEknight

or, just this:

d.setMonth(d.getMonth()+5)
d.setDate(0)

CFDevHead

ASKER

this d.setDate(31) can actually be anything betwwen 1 and 31 so that would not work

knightEknight

you can do setDate(0) and it will set the date back by 1 .. you can do setDate(99) and it will advance the date by 3 months and 9 days (give or take a few days)

knightEknight

... so advance to the first of the next month, and then go back one day and you land on the last of the previous month :)

cLFlaVA

Worked for me.

ASKER CERTIFIED SOLUTION

GwynforWeb

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GwynforWeb

Are you looking for the last day of the month 5 months in advance? if so then

<script>
function lastDay(val){
now=new Date(val)
last=new Date(now.getYear(),now.getMonth()+5,0)
return last
}

d='1/3/2004'
alert(d+' '+lastDay(d))
d='9/30/2004'
alert(d+' '+lastDay(d))
d='10/12/2004'
alert(d+' '+lastDay(d))
</script>

GwynforWeb

thx for the points :-)